Noncorrodible object and method of producing same



Dec. 21, 1937. F. P. ROMANOFF NONCORRODIBLE OBJECT AND METHOD OF PRODUCING SAME Filed April 23, 1936 w 7 A Q m Patented Dec. 21, 1937 w NONCOTLBODIBLE OBJECT AND METHOD OF PRODUCING SAME Frank r. nomauon, Chicago; 111., assignor to Apollo Metal Works, Chicago, 11]., a corporation of Illinois Application April 23,

1 Claim.

This invention relates to metallic objects and more particularly to objects fabricated from normally corrodible sheet metal, the. purpose of the invention being primarily to produce a sheet metal object having those surfaces whichare exposed to view plated and those surfaces not so exposed protected against corrosion by a iustprooflng coating.

Many articles of commerce and use are fabrilo cated from lightweight sheet metal which, for the sake. of appearance and durability of the finished article, is coated before fabrication with a non-corrodible metal such as nickel, chromium, or the like, such coatingsbeing applied by the usual electro-plating process.

The fabrication of such sheets into. the flnished articles, however, usually involves piercing orpenetration of the plated sheet by cutting or stamping the same to shape, and .often by 20 cutting, punching, or stamping holes or slots or slitsin the sheet. After being pierced in this manner the sheets are thenformed by bending operations into the desired shape of the finished 1 object. The cutting, punching, or other piercing operations performed upon the sheets results in the exposure along or around the edges of the cuts of the raw metal of the sheet between the plated surfaces. Sometimes also the stretching of the platedsheets by the drawing or bending operations cracks or breaks the surface plating so as to expose the underlying sheet metal. In

time these exposed surfaces corrode or oxidize so as to presentan unsightly appearance and in some articles, even though such corroded edges or the metal where the plating has become separated may not be exposed to view, the corrosion may stain and discolor other portions of the assembly of which the fabricated sheet metal object is a part, or may result in injury by dis- D coloration or otherwise to other articles or objects with which the corroded surfaces may be brought in contact.

a This objectionable corrosion of the exposed edges or portions of articles fabricated from predeterrent to the use of such pre-plated sheets in the production of many articles-for which such sheets would otherwise be highly desirable. Attempts have been made to overcome the difficulty by fabricating the articles from unplated metal sheets and subsequently plating the completed article, but the time and expense involved in plating articles already fabricated to shape as compared with pie-plating the metal in sheet form is so great asto practically preclude this plated sheet metal has heretofore constituted a.

practice. The purpose of my present invention is to enable the fabricator of the sheet metal articles or objects to fabricate them from preplated metal sheets in the usual manner and then to economically render the metal surfaces ex- 5 posed by the fabrication steps non-corrodible so that no portion of the completed article will thereafter be subject to corrosion.

The cost of rendering the completed sheet metal objects proof against corrosion being a 10 highly important factor in their commercial pro- I duction, myinvention aims to render such objects non-corrodible in a very expeditious and economical manner so that my method can be practiced to secure the desired results without 5 material increase in' the cost of production of the objects so treated.

In addition to the'type of articles above mentioned, the fabrication of, which involves the piercing of the metal sheet, there are other types of articles the fabrication of which involves only bending operations without piercing or materially stretching the sheet. For the production of many of these, a metal sheetplated on one face only would meet the requirements pro "vided the opposite faceof the sheet were not subject to corrosion. 'Heretofore, however, in order to insureagainst corrosion of the concealed surfaces in the fabricated article, as well as to prevent corrosion of the exposed surface 6 and render such exposed surface attractive in appearance, the plating of all surfaces ,at'con siderable expense has been considered necessary.

. Another, purpose of my invention, therefore, is to reduce the cost of production of articles of this character by elimm' ating the plating of thatsurface 0 the sheet which becomes concealed in the completed fabricated object, while at the same time rendering such concealed surface non-corrodible, by a method much cheaper than plating. 40 This purpose is accomplished in accordance with my invention by plating, one surface only of such a sheet and subjecting the unplated surface to the action of 'a corrosion'resistant agent which I renders such surface non-corrodible without in any way injuring or diminishingthe effectiveness or appearance of the previously plated surface.

Other objects and advantagesof my invention will be readily appreciated asthe same becomes better understood by reference to the following description when considered in connection with the accompanying drawing.

Referring to the drawing,

Fig. 1 is a perspective view of a metal sheet, all exposed surfaces of which have been plated; 66

Fig. 2 is a perspective view of the sheet of Fig. 1 after it has been subjected to a piercing fabricating operation;

Fig. 3 is a fragmentary sectional view on an enlarged scale through the sheet of Fig. 1;

I Fig. 4 is a similar view through the fabricated sheet of Fig. 2

Fig. 5 is a sectional view illustrating two metal sheets contiguously arranged so that when electro-plated the metal coating is applied to one face and the edges only of each sheet, as illustrated; and

Fig. 6 is a similar view of one of the sheets shown in Fig. 5 after it has been subjected to the action of a rustproofing agent.

It should-be at once noted that in the illustrations on the accompanying drawing the thickness of the sheets, and also the coatings thereon, are

' greatly exaggerated. While my invention, of

course, is applicable to sheets of almost any thick-' ness, its most profitablefleld of commercial utility is found in connection with articles made from relatively light gauge sheet metal.

In carrying out my improved method in accordance with the disclosure of Figs. 1 to 4, inclusive, a metal sheet of any desiredsize and thickness is first subjected to an electro-plating operation by which all exposed surfaces, including both faces and the edges of the sheet, are electro-plated with the desired metal, such .as chromium or nickel, for instance. Such a sheet is indicated in Fig. 1 of the drawing byreference character I, and the metal coating applied to the surface thereof, commonly termed plating, is indicated in Fig. 3 by reference character 8. Such plated sheets are sold by the manufacturer thereof to the fabricator, who shapes and forms them into the desired objects by fabrication processes which usually include not only operations which bend the sheet into form but also operations whichinvolve piercing the sheet by cutting, punching, stamping, or other similar operations. For illustrative purposes the partially fabricated sheet shown in Fig. 2 has been subjected to cutting operations which removed two of the corners, leaving exposed edges 9 and II and also provide perforations I2, thewalls of which present exposed metal surfaces between the plated surfaces of the sheet.

It will be obvious that if such a cut and punched sheet were now formed by bending operations into a completed article, such article would present unplated surfaces where the cutting and punching was perform :d which would be subject to corrosion. In accordance with my invention these exposed metal surfaces are made rustproof or non-'corrodible by subjecting them to the action of a rustproofing or corrosion re- While various solutions may be utilized for pro-- ducing the desired rustproofing effect, the preferred rustproofing coating comprises a chemical which has a phosphate base resulting in the for,- mation of a phosphate coating on exposed surfaces of the sheets subjected to such solutiom' The coating operation is purely a chemical action which takes place readily when the object is submerged in a bath containing the coating solution. For instance, the solution may contain manganese phosphate which chemically reacts with the steel or similar metal of the sheet to form a coating of phosphate of iron on the exposed surface-of the sheet. Satisfactory results may also be obtained by submersion of the article to be coated in a phosphoric acid bath, and there are also available various soluble powders comprising phosphate compounds adapted when in solution to chemically react upon the exposed metal surfaces of the object to be coated to deposit upon such surfaces a rustproof phosphate coating.

.As previously stated, .the chemically created phosphate coating is readily formed upon the exposed surfaces so that the time required for submersion in order to produce an average coating is not excessive.

Since the solution itself is not expensive to produce the entire cost of the method both as to time and materialsis modthe sheets is illustrated in Fig. 5, wherein the sheets I! and I3 are disposed face to face and in this position subjected to the plating operation which deposits a coating H on the outer faces and edges only of the sheets, leaving the contiguously disposed faces unplated. 'After being plated the sheets'are then separated. and immersed in the corrosion resistant bath which results in the formation of a non-corrodible coating I5 on the unplated surface of the sheet. The resultant sheet accordingly has a corrosion resistant coating on one face and is plated on the opposite face and on the edges, so that all of the surfaces are covered and protected. Such sheets are suitable for fabrication without further coating treatment in the production of those articles or objects the fabrication of which does not require any piercing or penetration of the sheet. For some purposes a sheet plated ,on both sides with the edges unplated but rendered corrosion resistant is desirable. My invention is obviously suitable for the production of such sheets also.

The details of the method which has been described as illustrative may obviously be varied within considerable limits within the scope of the invention as defined in the following claim.

I claim:

The method of making a non-corrodible sheet metal article which comprises producing by electrolytic deposition upon the exposed portions of a metal sheet a metal coating resistant to at- Y tack by a rustproofing phosphate base solution, fabricating the thus electroplated sheet to form an article of the desired shape in which portions of the base metal of the fabricated sheet are left exposed, and rustproofing said exposed portions without affecting the previously electroplated portions of the article by immersing the article in a rustproofing phosphate solution.

FRANK P. Romor-F. 

